org.unict.ing.pds.dhtdb.datamanager.lightBeans

Class LightSessionBean

java.lang.Object

org.unict.ing.pds.dhtdb.datamanager.lightBeans.LightSessionBean

All Implemented Interfaces:

LightSessionBeanLocal

public class LightSessionBean
extends Object
implements LightSessionBeanLocal

This beans is a singleton. It stores the height of the tree in runtime. The height is also stored in the MASTER_NODE to provide a "safe" boot (This is just a workaround, there are several ways to estimate in a distributed way the height of this kind of tree, see PHT). The MASTER_NODE could be replicated, the fault tolerance about its datas is provided by the overlay network. Still, this singleton is responsible for the operations of tree splitting. These are done in LockWrite so that concurrent put doesn't make the distributed database inconsistent

Field Summary

Fields

Modifier and Type	Field and Description
private javax.ejb.SessionContext	context
(package private) DataManagerChordSessionBeanLocal	dataManagerChordSessionBean
private LookupSessionBeanLocal	lookupSessionBean
private static int	PERIOD The period to update the tree height in the master node
static int	TETA_SPLIT
private static Key	TREE_HEIGHT_KEY We know the key of the MASTER NODE, just for simplicity we are using a Key that is just 1_16 less than MASTER_NODE key
private int	treeHeight Initial tree height

Constructor Summary

Constructors

Constructor and Description
LightSessionBean()

Method Summary

Modifier and Type	Method and Description
void	checkTreeHeight(Label label) Called to check, in run-time, the height of the tree using the length of a Label
int	getTreeHeight()
void	init()
private DataManagerChordSessionBeanLocal	lookupDataManagerChordSessionBeanLocal()
private void	setRemoteTreeHeight() This is called periodically, it sets the treeHeight consistent between the DataManager and the distributed DB
void	setTreeHeight(int treeHeight) Updates the treeHeight with the given argument
Bucket	splitAndPut(Bucket localBucket, long timestamp, GenericStat elem) Split the distributed tree and migrates the datas in the new Bucket (s)
void	timeout(javax.ejb.Timer timer)

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

TETA_SPLIT

public static final int TETA_SPLIT

See Also:

Constant Field Values

lookupSessionBean

private LookupSessionBeanLocal lookupSessionBean

PERIOD

private static final int PERIOD

The period to update the tree height in the master node

See Also:

Constant Field Values

dataManagerChordSessionBean

DataManagerChordSessionBeanLocal dataManagerChordSessionBean

TREE_HEIGHT_KEY

private static final Key TREE_HEIGHT_KEY

We know the key of the MASTER NODE, just for simplicity we are using a Key that is just 1_16 less than MASTER_NODE key

treeHeight

private int treeHeight

Initial tree height

context

private javax.ejb.SessionContext context

Constructor Detail

LightSessionBean

public LightSessionBean()

Method Detail

init

@PostConstruct
public void init()

timeout

public void timeout(javax.ejb.Timer timer)

setRemoteTreeHeight

private void setRemoteTreeHeight()

This is called periodically, it sets the treeHeight consistent between the DataManager and the distributed DB

checkTreeHeight

public void checkTreeHeight(Label label)

Called to check, in run-time, the height of the tree using the length of a Label

Specified by:

checkTreeHeight in interface LightSessionBeanLocal

Parameters:

label - |

getTreeHeight

public int getTreeHeight()

Specified by:

getTreeHeight in interface LightSessionBeanLocal

setTreeHeight

public void setTreeHeight(int treeHeight)

Updates the treeHeight with the given argument

Specified by:

setTreeHeight in interface LightSessionBeanLocal

Parameters:

treeHeight - |

splitAndPut

public Bucket splitAndPut(Bucket localBucket,
                          long timestamp,
                          GenericStat elem)

Split the distributed tree and migrates the datas in the new Bucket (s)

Specified by:

splitAndPut in interface LightSessionBeanLocal

Parameters:

localBucket - |

timestamp - |

elem - |

Returns:

|

lookupDataManagerChordSessionBeanLocal

private DataManagerChordSessionBeanLocal lookupDataManagerChordSessionBeanLocal()